Stone accumulates naturally through mining copper and silver. Be sure to have the resources for a workbench, 1-2 chests, and a safe portal to go back for comfort and repairs - technically you could also make a covered forge for repairs and comfort when using it.

Plains is really good for acquiring stone with the giant pillars + you can easily spot them and stone boulders that you can also break down. Again... just wander around with a portal and be somewhat careful using Root Chest Armor to deal with Deathsquitos / Fuling Spear Chuckers.

Mistlands can also yield a lot of stone but obviously that biome is far more dangerous imo + it can be more difficult to navigate due to sheer terrain and the annoying mist mechanic.

You can also get stone from mountains as it's pretty easy to spot boulders / rocks and killing wolves or drakes can still yield decent resources.